Studies are planned to characterize the relationship between dietary intake and sympathetic activity. The techniques involve measurements of norepinephrine turnover in the experimental animal and plasma norepinephrine and urinary catecholamine excretion in man. The effect of various diets will be tested and correlation with changes in blood pressure will be made. The special problem of fasting in pregnancy in the rat and its effect on activation of the sympathoadrenal system will be assessed.